Resilient retaining means



y 7, 1968 H. KIEFER 3,382,005

RESILIENT RETAINING MEANS Filed Sept. 15, 1966 2 Sheets-Sheet 1 5/ MW W May 7, 1968 H. KIEFER 3,382,005

RESILIENT RETAINING MEANS Filed Sept. 15, 1966 2 Sheets-Sheet 2 ea i 5 70 l I 2 United States Patent 3,382,005 RESILIENT RETAINING MEANS Henry Kiefer, Painesville, Ohio, assignor to Eagle-Picker Industries, Inc., Cincinnati, Ohio, a corporation of Ohio Filed Sept. 15, 1966, Ser. No. 579,718 8 Claims. (Cl. 299-92) This invention relates to resilient retaining means. More particularly, this invention is directed to a resilient holder especially adapted for securing a mining bit in a power driven cutter, also permitting ready assembly and extraction of the bit in a cooperating socket member.

Bit holders are commonly used to provide a snap in type connection of the bit into the socket, in which the bit holder engages the bit in the manner of a spring loaded detent. The construction of such resilient holders for mining bits or tools presents a rather unique bundle of special considerations. The holders must be capable of securely retaining the mining bit against high frequency vibrations during mining operations. Yet, too much holding power prevents easy extraction of the bits which have to be replaced often because of wear or different cutting conditions. The resilient holder itself must be resist-ant to the abrasive action of coal or ore dusts, and should be easily insertable into the cooperating socket member with a minimum of effort and equipment; and, when necessary, readily removable.

Conventional bit holders generally employ a body of rubber in their structure to absorb or dilute the vibrational forces acting on the cutter bit. It has been previously determined, however, that such resilient material will deform or spread under the forces of operation and often does not provide sufificient bit holding power. Steel jackets and outer anti-spread members have been proposed to supply stifiness and outer support to the body of rubber.

The steel jacketed prior art bit holders have been found to be unwieldy, because the holder must be hammered into the bit socket member and a misdirected blow can distort the jacket and render the bit holder useless. Also, after continued use, the steel jacketed holder may become jammed in the socket member and considerable efiort may be required to force it out when replacement becomes necessary.

Other bit holder designs have been proposed, in the hope of eliminating the need for a steel jacket, in which a body of rubber is molded about an elongated steel rod or pin. The pin projects into the end portions of the rubber body to provide support against spreading or deformation of the rubber upon bit insertion, and an opening in the body exposes the central part of the pin to the bit shank. Nonetheless, in practice even these constructions still usually require outer jackets for support and holding power, yet they provide only relatively low bit-holding force.

It has been an objective of this invention to provide improved resilient retaining means especially adapted for more adequately securing a mining bit in its socket against the vibrational forces occuring during mining operations.

It has been another objective of this invention to provide a mining bit holder which permits both assembly and extraction of the mining bit from its socket with a minimum of effort and equipment.

Iti s a further objective of this invention to provide a resilient bit holder which eliminates the need for any outer metal packet and the disadvantages associated with the use of such outer jackets.

Another objective of this invention is to provide a bit holder which can be replaced when necessary by merely exerting pressure with the thumb of a hand.

It is a further objective of this invention to provide a resilient bit holder with component parts which are readily assembled, as by hand, eliminating unnecessary equip- 3,382,005 Patented May 7, 1968 ment, procedures, and expense associated with present techniques of molding rubber about metal rods as in conventional holders.

In accomplishing the above objectives, in accordance with this invention, the mining bit holders are able to be constructed with a considerable reduction in overall weight and with great resistance to abrasion by utilizing certain novel features of construction and materials. Other objects and advantages of this invention will become apparent from the following description of the invention.

The present invention is predicated, in part, upon the concept of providing a mining bit holder in which a plug-in type metal detent member is mounted entirely within the axial limits of a slot in an elastomeric body.

A preferred form of this mining bit holder includes an elastomeric body which is in the general form of a cylinder having a transverse slot extending across its axis and an opposite external longitudinal rib. In the center of the slot base an axial recess is formed which extends only from side to side of the slot. Preferably two seats or cavities are formed in the body, which project perpendicularly from the axis toward the rib from the bottom of the recess between the slot sides. A generally C-shaped steel detent member resides entirely within a space bounded by the side surfaces of the body slot, and has a pair of parallel legs which project into the cavities of the holder and a rounded axial edge seated or cupped within the axial recess in the slot.

Referring to the drawings:

FIGURE 1 is an exploded view in perspective of a preferred form of the resilient retaining means according to this invention, also showing a typical mining bit and bit socket member.

FIGURE 2 is a side view of a mining machine cutter drive chan, partly broken away, showing in side elevation and in partial section the assembly of components of FIGURE I mounted on the cutter chain.

FIGURE 3 is a cross-sectional view of the bit assembly, taken along the line 3-3 of FIGURE 2.

As shown in the drawings, a mining bit holder 1 embodying a preferred form of this invention is employed with a typical mining bit 2 and a typical socket member 3 which has an opening or socket 4 for receiving the shank 5 of the mining bit. Socket member 3 also has a cross bore 10 which receives the resilient bit holder, the bore 16 intersecting socket 4 on one side thereof.

In FIGURE 1, the bit holder 1 is in the form of a generally cylindrical body 14 of elastomeric or resilient material having a central transverse slot 15 extending across its axis which receives a metal detent member 16. A longitudinal rib 17 is formed on the external surface of body 14 on the side thereof opposite the transverse slot 15.

The cylindrical body 14 has tapered end surfaces by which it can be pressed into and extracted from the bore 10 of the socket member 3, as by applying pressure with the thumb. The rib 17 acts as a key which cooperates with an internal groove 20 of the bore 10 to prevent rotation of the cylindrical body 14 about its axis when inserted in the socket member 3. The axial key or rib 17 also aids in the vertical alignment of the slot 15 with the socket opening 4.

The slot 15 defines interior sides 19, 21 within the body and an interior base portion 22. Slot sides 19, 21 are substantially perpendicular to the base portion 22, the base portion preferably intersects the axis of the body (FIG- URE 3). The axial dimension of slot 15' may be approximately equal to the Width of socket 4. In the interior base portion 22 of the body 14, a longitudinal recess 25 is formed opposite the external rib 17 and extending perpendicularly to and between sides 19 and 21. Formed in the end portions of the recess 25 are internal seats or cavities 27, 28 which perpendicularly extend toward the external rib 17 portion of the body 14, as best seen in FIGURE 3. The cavities 27, 28 have axially outermost side walls 30, 31 which are coplanar with the respective slot side surfaces 19, 21.

The recess 25 and the cavities 27, 28 formed in the interior base 22 portion of the transverse slot of the cylindrical body 14, mount the generally C-shaped metal detent 16, The metal detent has a pair of substantially parallel legs 40, 41, each of squared cross-section and integrally joined to a wider central bridge or cap portion 42. The bridge or cap 42 has rounded outer longitudinal edge 50 (FIGURE 2) opposite the detent legs 40, 41. The opposed end surfaces 52, 53 of the bridge are continuations of the outer sides 60, 61 of the integral detent legs 40, 41.

The C-shaped detent 16 is dimensioned just to fit between the sides 19, 21 of the transverse slot 15 in holder 1, with the detent legs 40, 41 received or press fitted, in

the body cavities 27, 28. This assembly eliminates the conventional process of molding the rubber in situ about a metal insert. The base of the detent bridge portion 42 is seated in body recess 25, so that the rounded axial edge 51 of the bridge 42 is exposed in slot 15 for gripping the bit (FIGURE 2). To this end the depth of recess 25 is preferably about /3 the height of bridge portion 42.

.As best shown in FIGURE 3, the depth of the interior cavities 27, 28 formed in retainer 1 is such that when the detent legs 40, 41 are inserted and the cap 42 is seated in the recess 25, conforming gaps 70, 71 are formed between the ends of the detent legs and the inner ends of the cavities. These gaps 70, 71 permit resilient movement of the C-shaped detent 16 toward the opposite external longitudinal rib 17 by compression of the body 14 of the bit holder 1 when a cutter bit shank 5 is driven into the socket opening 4. This avoids the end spreading which has plagued previous resilient bit holders. Thus, cutter bit 2 is secured against vibratory forces for normal operations of the mining bit assembly (FIGURE 2). Yet, when the cutter bit 2 is to be replaced, a minimum of effort is required to remove it by prying it from the socket memher.

It is to be noted in FIGURES 2 and 3 that the inner chambers or gaps 70, 71 are in effect sealed off by the detent legs 40, 41 and the cap 42 which is seated in recess 25 of slot 15. This construction serves to guard against or minimize the entrance of coal or ore dust and corrosive water into the inner chambers which provide the snap-action" of the metal detent 16 under compression.

The bit holder of this invention can suitably be made of polyurethane or other elastomeric material providing high compression modulus, high resilience and resistance to abrasion. I prefer to use a polyether polyurethane having a durometer D hardness of about 50.

Having described my invention, I claim:

1. A resilient retaining means comprising:

a body of elastomeric material having a slot formed in a side of said body, said slot defining interior sides and an interior base, said interior base having a cavity formed therein extending toward the side of the body opposite the interior base, and

a rigid metal detent having a cap portion with opposed ends and a leg portion integrally joined to said cap portion at a point between said opposed ends, said detent mounted in said slot with said detent leg lying in said interior base cavity, and said detent cap seated on said interior base with said detent cap ends lying within the sides of said slot, the end of said detent leg lying away from the end of base cavity thereby providing an inner gap.

2. The retaining means of claim 1 in which said body comprises a cylinder with said slot transversely across its axis and an external longitudinal rib formed on the side of said cylinder opposite the slot.

3. The retaining means of claim 1 in which said detent has two spaced parallel leg portions both joined by said cap portion.

4. A bit holder comprising,

a generally C-shaped metal detent having a central bridge portion and a pair of legs projecting at right angles from said bridge portion adjacent the ends thereof,

and a body of resilient material in the general shape of a bar having a transverse slot defining an interior base and opposed interior side walls, a longitudinal recess formed in said body in said interior base and terminating in the planes of said side walls, and a pair of openings projecting into said body from said recess,

a part of the height of said bridge portion of said detent being seated in said recess, said bridge portion having an exposed surface thereon extending into said slot for engaging a bit, said legs closing and being gripped within the openings of said body, said legs terminating short of the ends of said openings.

5. The bit holder of claim 4 wherein the axially outermost surfaces of said legs are coplanar with the ends of said bridge portion of said detent.

6. The bit holder of claim 4 wherein said body is in the form of a cylinder having tapered ends and a longitudinal rib on the side thereof opposite said slot.

7. The bit holder of claim 4 wherein said body is made of a polyether polyurethane.

8. A resilient retaining means comprising,

a body of elastomeric material having a transverse slot formed in a side of said body, said slot defining interior sides and an interior base and a rigid member having a central bearing portion with opposed ends and at least one leg portion integrally joined to said central portion between said opposed ends, said rigid member mounted in said slot with said leg portion gripped by said body within said interior base and said central portion seated on said interior base with said opposed ends lying within the sides of said transverse slot.

References Cited UNITED STATES PATENTS 3,063,691 11/1962 Osgood 29992 3,116,052 12/1963 Osgood 299-92 3,275,376 9/1966 Prox 29992 3,351,386 11/1967 Prox 299-92 ERNEST R, PURSER, Primary Examiner. 

8. A RESILIENT RETAINING MEANS COMPRISING, A BODY OF ELASTOMERIC MATERIAL HAVING A TRANSVERSE SLOT FORMED IN A SIDE OF SAID BODY, SAID SLOT DEFINING INTERIOR SIDES AND AN INTERIOR BASE AND 